Need to ask a number of questions:
1. What exact Mac model do you have?
2. What exact Mac OS are you using?
3. Have you ever done an disk cleanup/maintenance/repairs, from a software perspective? By that I mean have you ever run any disk-related software to help with those tasks? There are some excellent products available (both free and commercial) that can help you with that.
4. This is critical: are you making backups to an external device? If yo are, what software are you using for that?
5. Besides Microsoft Project (is that Project 2016?), what other third party (ie, non-Apple) software do you have? For those that you have, did you insure that they are compatible with the Mac OS you are running?
6. How much free space do you have on your internal drive?
7. If you have either MacKeeper or CleanMyMac installed, you need to get rid of them IMMEDIATELY. Either of them cause more harm than good, and there are a number of excellent freeware programs that do as good, or in some cases, better job than either of them. And they are proven, reliable, and rock solid.
8. How did you upgrade to the Mac OS you are using? Did you just upgrade "in place", ie, have the new Mac OS basically overwrite what was on your machine already?